- Mechanochemically induced cross-dimerizations of nitrosobenzenes. Kinetics and solid-state isotope effects
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Mechanical treatment (milling) of crystals of aromatic nitroso dimers (azodioxides) induces their dissociation and cross-dimerizations. The mechanisms of these processes are discussed on the basis of kinetic studies and the solid-state 15 N kinetic isotope effect, which is measured for the first time. By comparison with analogous processes in cocrystals and in melts, it appears that the reactions follow similar mechanism in which the surface deformations play the crucial role. The system can also be used as a model for a more general conceptual study of solid-state reaction mechanisms. Copyright
- Maganjic, Ana,Solic, Ivan,Milovac, Srd Strok Signan,Halasz, Ivan,Biljan, Ivana,Vancik, Hrvoj
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p. 177 - 182
(2014/03/21)
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- Photothermal reactions of nitrosobenzene and halonitrosobenzenes in solid-state
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Photothermal reactions of the dimers of nitrosobenzene, m-chloronitrosobenzene, and p-chloronitrosobenzene were studied in solid-state by IR spectroscopy at low temperatures and by X-ray powder diffraction. It was found for the first time that photothermal cycle (photolytic dissociation fol-lowed by thermal dimerization) could successively be performed also with Z-configured dimeric nitroso-benzene. Halonitrosobenzenes dimers with E-configuration afforded different photo behavior depending on the po-sition of halogen atom on the benzene ring: while m-halonitrosobenzenes do not dissociate under UV ir-radiation, p-chloronitrosobenzene, as well as previously studied p-bromonitrosobenzene photolyses very efficiently with recovering of the original crystal phase. Kinetics of thermal dimerization was measured in solid-state, and it was found that the reaction phase transformation occurs as a two-dimensional growth through the crystal.
- Knezevic, Anamarija,Medancic, Tina,Milovac, Srdan,Biljan, Ivana,Halasz, Ivan,Vancik, Hrvoj
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scheme or table
p. 21 - 24
(2012/02/15)
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- Oxidation of Aromatic Amines with Hydrogen Peroxide Catalyzed by Cetylpyridinium Heteropolyoxometalates
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Various substituted anilines 1 were selectively converted into the corresponsing nitrosobenzenes 2 or nitrobenzenes 3 by oxidation with aqueous hydrogen peroxide catalyzed by heteropolyoxometalates.The oxidation of anilines 1 with 35percent H2O2 catalyzed by peroxotungstophosphate (PCWP) at room temperature in chloroform under two-phase conditions afforded nitrosobenzene 2 with high selectivity.When the same reactions were carried out at higher temperature (e.g., refluxing chloroform), nitrobenzenes 3 were obtained in good yields.The oxidation of aniline (1a) with dilute H2O2 catalyzed by PCWP (2 wtpercent) in an aqueous medium produced azoxybenzene (4a) with high selectivity.Phenylazoxyalkanes 7 were prepared by the first direct cooxidation of 1a in the presence of primary aliphatic amines 6.For example, the oxidation of a 1:2 mixture of 1a and hexylamine (6b) with 35percent H2O2 (6 equiv) in the presence of PCWP produced phenylazoxyhexane (7b) along with a small amount of 4a (8percent).The reaction path for the conversion of anilines to azoxy-, nitroso-, and nitrobenzenes is described.
- Sakaue, Sigeki,Tsubakino, Takashi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 3633 - 3638
(2007/10/02)
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- Oxidation of Aliphatic and Aromatic Amines with Hydrogen Peroxide Catralyzed by Peroxoheteropoly Oxometalates
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Peroxotungstophosphate (PCWP) was found to be an efficient catalyst for the oxidation of amines with 35percent H2O2 under the biphasic or homogeneous condition.Thus, primary and secondary amines were oxidized to oximes and nitrones, respectively, in good yields.Aromatic amines afforded to the corresponding nitroso compounds and/or nitrobenzenes.
- Sakaue, Shigeki,Sakata, Yasuyuki,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 289 - 292
(2007/10/02)
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